Thread: probability values

Hello, I need help, which of the following represent valid probibility values?
0
100%
-0.8
0.001
thanks again

Originally Posted by mkcar

Hello, I need help, which of the following represent valid probibility values?
0
100%
-0.8
0.001
thanks again

when written in terms of a decimal, a valid probability value, call it P, ranges from

when written as a percentage: 0 % 100%


Note: when an event is certain, it has a probability of 1 or 100%, when an event is impossible, it has a probability of 0

Originally Posted by Jhevon

Note: when an event is certain, it has a probability of 1 or 100%, when an event is impossible, it has a probability of 0

But not the other way around. An event can be possible and still have probability 0, and not be certain and have probability 1.

RonL

How? By subjective probability from intuition, guesses, and estimates?

Originally Posted by rualin

How? By subjective probability from intuition, guesses, and estimates?

What are you refering to?

RonL

Originally Posted by CaptainBlack

But not the other way around. An event can be possible and still have probability 0, and not be certain and have probability 1.

RonL

Sorry, I forgot to quote. My question was, "How can it be that an event that's possible has a probability of 0 and one that is not certain has a probability of 1?"

Originally Posted by rualin

Sorry, I forgot to quote. My question was, "How can it be that an event that's possible has a probability of 0 and one that is not certain has a probability of 1?"

Suppose the lengths of rods are distributed normaly with mean mu and sd sigma.

Then it is possible for a rod to have length mu+signa/3, but the probability that it does is zero.

This is a toy construction but there are real cases where this can be important (fractal noise
comes to mind).

RonL